Support Settings: Type, Density and Top Gap

Supports exist to hold up geometry the printer can't bridge on its own, and the two decisions that matter most — support type, and how much gap to leave between support and part — are exactly the ones most people leave on default and then blame the model for.

Normal vs tree supports

Normal (grid) supports build straight columns under overhangs — simple, strong, and easy to predict, but they use more material and leave more contact scarring on flat undersides. Tree supports branch outward from fewer contact points, following the geometry more efficiently — better for organic shapes and easier removal on complex overhangs, at the cost of being less predictable to tune by hand. Bambu Studio's Type setting offers auto-generated and enforcer-only ("manual") variants of both; auto is the right default for most models, with manual supports reserved for the specific spots auto-detection misses.

The setting that actually determines removal quality: top gap

The vertical gap between the top of a support and the part above it — Bambu Studio calls it Top Z distance — controls how hard the two fuse together. Too small a gap and the support welds to the part, leaving a torn, rough surface after removal — worse in materials that bond eagerly to themselves, which is exactly the trade-off the ABS/ASA bridging guide and PETG comparison both flag: PETG in particular welds to its own supports far more eagerly than PLA, so it needs a more generous gap (roughly 0.2–0.25 mm) than PLA typically does to release cleanly.

PVA: the one genuinely clean support material

Every support strategy above still leaves some mark on the part. PVA is different: it's water-soluble, dissolving away entirely and leaving the contact surface untouched — the only approach in our knowledge base that removes supports without any mechanical scarring at all. The trade-off is print complexity (a second material, a dual-extrusion or AMS-capable setup, and PVA's own strict drying requirements) and cost, which is why it's reserved for parts where surface quality under an overhang genuinely can't be compromised.

Practical guidance by material

• PLA: normal supports with a modest gap (0.1–0.15 mm) remove cleanly in almost every case.
• PETG: generous top gap (0.2–0.25 mm) or expect a rougher release — PETG's layer-welding strength works against you here.
• ABS/ASA: tree supports with a hot chamber fuse harder than on an open printer; budget the gap accordingly and consider a slightly larger value than the PLA default.
• Overhangs you can redesign instead: a 45° chamfer instead of a 90° ceiling often beats tuning supports entirely — see the bridging guide for the general design-around-it playbook.